ray poulton wrote:advice reqd please . any thing further to disconnect , having disconnected the battery and alternator? I am going to weld the rear cross member and brackets for my new rear bumper .

You've already disconnected more than I ever do

You've got me worried now - I guess you are thinking of the electronic modules as well? I really hope that it's not necessary to disconnect them since I haven't done, and so far I have expended 11lbs of welding wire on it! (front, offside and back done - one more side to go now)

Since you are having to weld brackets for your rear bumper - does that mean it's home made? If so I'll be interested to see it - will it be out to play at Greenhow?

They seem to be pretty bomb proof as far as electrics and electric welding go. I normally disconnect the battery because I have a cut off switch to do it for me

The main thing is to make sure your earth clamp has a good connection and is as close to the welding area as possible, that way you're very unlikely to get stray current getting to places you'd rather it didn't.

If you are feeling particularly paranoid you cold unplug the engine ECU too but I never bothered.

I usually (always unless I forget) disconnect the battery and alternator, it has been known for the rectifier packs on the alternator to blow when leaving it connected (old ACR alternators), don't worry about owt else it should be fine with the above 2 disconnected.
Matthew

ray poulton wrote:advice reqd please . any thing further to disconnect , having disconnected the battery and alternator? I am going to weld the rear cross member and brackets for my new rear bumper .

The best thing to do is to disconnect the battery then join the positive /neg terminals together then earth this junction
I have carried this out on several vehicles
What you will then have is all the main vehicle conductors at one potenial ie earth so that the welder is not able to induce a highish voltage on to any feeds The profesionals connect a device acrosse the battery which puts a short cct to any AC voltage that may be induced
You should not have a problem
Dave Willard

Ray, the important thing is to ensure you have a good earth close to where you are welding to prevent tracking. Clean up a spot on the new crossmember and put the earth clamp on there remembering to remove any paint from the area you are welding.
Have fun.
Bo